The present invention relates to the field of storage containers and closure assemblies for securing storage container lids or covers to the open ends of storage containers, and, more specifically, the present invention relates to an improved closure ring assembly used to secure a drum lid to an open-head drum.
Open-head drums are commonly used as containers for storage and transportation of bulk materials. These drums have a cylindrical opening to receive materials, and they conventionally include an annular closure ring assembly to secure a lid or similar covering around the cylindrical opening of the drum. To meet governmental regulations and industry standards, the closure ring assemblies of these drums must be able to withstand being tested by being dropped onto a rigid, non-resilient, smooth, flat and horizontal surface, where the point of impact is the most vulnerable part of the base of the intermediate bulk container being tested. Following the drop, the intermediate bulk container is examined to verify that the seal is maintained and that the contents are protected. Therefore, to meet these test requirements, a reliable closure ring assembly must be provided.
Failures with open-head drums frequently occur in the steel drum industry. Conventional open-head drums face hydrostatic leaks that occur when the drums are either improperly sealed or placed in heated areas where a build up of pressure can occur. Furthermore, conventional open-head drums also face drop failure due to improper sealing methods or by being accidentally dropped from a truck or rail shipment. To prevent hydrostatic and drop failure, several standards organizations developed hydrostatic and drop height limits.
A conventional closure ring assembly 10 is shown in FIGS. 1 and 2, which is similar to the closure ring assembly described in U.S. Pat. No. 5,584,410 issued to Siblik (xe2x80x9cthe Siblik patentxe2x80x9d). This closure ring assembly 10 includes the following elements: a split closure ring 12 having two adjacent ends 22, 24; a first lug 16 having a unthreaded hole 17; a second lug 14 having an threaded hole 13; a conventional bolt 18 having a threaded cylindrical member 15 and a head 19 (shown in FIG. 3); and a jam nut 20. A first lug 16 is attached to the first end 22 of the closure ring 12, and a second lug 14 is attached to the second end 24 of the closure ring 12.
To secure the lid to the opening of the drum, the closure ring 12 is placed around the lid and drum, and the threaded cylindrical member 15 of bolt 18 is inserted through the unthreaded hole 17 to engage the threaded hole 13. As the threaded cylindrical member 15 engages the threaded hole 13, the two ends 22, 24 of the closure ring 12 are drawn together to tighten the closure ring 12 around the lid and drum.
A common problem with the closure ring assembly 10 described above is the space 21 found between the bolt 18 and the unthreaded hole 17 (see FIG. 2). This space 21 allows undesired movement of the bolt 18 within the closure ring 12 when a force is applied to the drum, which allows movement of the closure ring 12. For example, if the drum is dropped or rolled, the space 21 between the bolt 18 and the unthreaded lug 16 allows movement of the bolt 18 such that the lugs 14, 16 become unaligned and the connection between the bolt 18 and the threaded lug 14 is affected, which can disrupt the sealed relationship between the lid and the drum and cause the lid to become displaced from the drum.
To compensate for this problem, a jam nut 20 (shown in FIGS. 1 and 2) is used to secure the assembly 10. The bolt 18 in this design is inserted through the unthreaded hole 17 and engages the threaded hole 13 to draw the two ends 22, 24 of the split closure ring 12 together around the open-head drum. The jam nut 20 is included in the assembly 10 to engage the threaded cylindrical member 15 and secure the lug 16 between the head 19 and the jam nut 20, which aids the closure ring assembly 10 to withstand impact forces without moving the bolt 18 within the space 21. However, a problem that arises with the use of the jam nut 20 is that the distance between the lugs 14, 16 is increased due to the location of the jam nut 20, thereby loosening the connection of the closure ring 12 around the lid and drum.
Additionally, other designs have been provided to achieve a seal for an open-head drum that prevents against the leakage of the contents therein. For example, U.S. Pat. No. 3,907,349 to Kane (xe2x80x9cthe Kane patentxe2x80x9d) describes an end closure ring assembly having an overlapping, light gauge ring that is used in an attempt to completely seal the drum. Light gauge rings as described in Kane conventionally have a width of approximately 0.052 inches. As a result, such rings are not able to securely attach lids as required by industry standards. Consequently, Kane further requires the ring to partially overlap to secure a lid to provide the most secure connection. Moreover, such a design requires epoxy or similar adhesive to keep from leaking.
What is needed, then, and not found in the prior art, is a closure ring assembly for open-head drums that will reduce the movement in the closure ring once the closure ring has been assembled on the drum and consequently provide a secure connection between the closure ring and the drum.
It is an object of the present invention to provide an improved closure ring assembly for use with open-head drums having a heavy gauge ring as required by industry standards that is able to secure a lid to the drum.
It is an object of the present invention to provide an improved closure ring assembly for use with open-head drums that overcomes the problem of undesired radial and axial movement of the closure ring.
It is another object of the present invention to provide an improved closure ring assembly for use with storage drums that eliminates the number of required elements between the lugs so that the closure ring may provide a tighter connection with the open-head drum.
These and other objects of the present invention are accomplished through an improved annular closure ring and bolt assembly used to secure a lid or cover to a conventional open-head drum. The annular closure ring is split to provide two adjacent ends that are capable of surrounding an open-head drum. Attached to the two ends are two lugs that have holes passing transversely through the lugs. A bolt is provided to intersect and engage the holes of the lugs to draw the lugs and the ends of the closure ring together around the lid and the drum.
More particularly, in the first embodiment of the invention, the first lug includes a purposely-large unthreaded hole that is necessary to eliminate cross threading and the second lug includes a threaded hole. The bolt is designed to pass through the large unthreaded hole to engage the threaded hole. To reduce unwanted movement between the large unthreaded lug and the bolt when the annular split ring is tightened around the lid and the drum, a shoulder is used with the bolt. The shoulder may be integrally formed onto the bolt, or it may be a slip sleeve or threaded sleeve that may be positioned by the head of the bolt. The diameter of the shoulder is designed to be slightly less than the diameter of the large unthreaded hole so that when the bolt engages the lugs, the shoulder is substantially flush with the periphery of the large unthreaded hole. The shoulder thereby reduces the movement that is allowable within the large unthreaded hole to secure the connection of the bolt to the lugs and reinforce the connection of the annular closure ring to the open-head drum.
Additionally, although not required, a jam nut may be included in this assembly to further secure the bolt to the lugs. The jam nut can engage the bolt between the lugs, as with conventional closure ring assemblies, to further secure the connection of the bolt.
In a second embodiment, both lugs include unthreaded holes. The bolt thereby passes through the unthreaded holes in the lugs to engage a jam nut which secures the bolt to the lugs. The shoulder of the bolt in this embodiment is extended so that it will be substantially flush with the periphery of the both holes when the closure ring is attached to the drum, which reduces the amount of movement allowable within the holes to secure the connection of the bolt to the lugs and to reinforce the connection of the annular closure ring to the open-head drum.
These and other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment of the invention.